The load-time gate (maybe_disable_chunked_prefix_cache) wrote its
ServerArgs instance while every reader has moved to the published
config: the attention backends assert / branch on
get_schedule().disable_chunked_prefix_cache when they initialize, so the
flip never reached them and a backend outside
CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS kept chunked prefix
enabled.
Reroute the writer through get_context().override (which writes the
published bags) and flip the two remaining instance reads — the gate's
own log check and the prefill cuda-graph runner's capture flag — to the
bag. A regression test pins the three contracts: the gate lands on the
bag, the pristine ServerArgs instance stays untouched, and the
draft-worker guard never writes.
The ServerArgs.override call-site ratchet drops 39 -> 38.
Cheng Wan
df55e911d6